Search

In this work, a reaction-based ratiometric and colorimetric sensor was designed and synthesized for probing bisulfite (HSO 3 - ) by coupling coumarin ( CM ) with barbituric ( BA ) moiety. Further tests have shown that CM-BA has high selectivity and sensitivity for the recognition of HSO 3 - , which can be applied for the detection of HSO 3 - in environmental and biological systems very effectively. The fluorescence intensity ratios ( F 462 / F 568 ) exhibited an outstanding HSO 3 - -dependent response with ultrafast response time (within 20 s) and a lower detection limit (105 nM). Meanwhile, the color of the CM-BA solution changed from green to colorless during the recognition process, and its fluorescence changed from green to blue. The mechanism of response is confirmed by the density functional theory (DFT) model. In summary, CM-BA has demonstrated low toxicity and good permeability, which can be applied for imaging HSO 3 - in cells and zebrafish safely and effectively. Besides, this novel sensor CM-BA successfully realized the quantification of the concentration of HSO 3 - in paper strips and food samples.

Sulfites are food additives found in a large variety of food products to help reduce oxidation and browning. A small subset of the population has "allergic-like" symptoms upon consumption of sulfite containing foods. There are several sulfite detection methods available in the literature that vary in analysis time and required instrumentation. There are also rapid screening tests available that have not been tested extensively for accuracy and precision. In this study, four different methods (an LC-MS/MS method, a spectrophotometric method, a test strip method and a spot test method) were used to determine the sulfite concentration of 10 different commercially sulfited products. Of these methods, the LC-MS/MS and the spectrophotometric method had the most comparable results. The test strips were only accurate at concentrations greater than 50 mg/kg (ppm) SO 2 . The spot test method was found to be inaccurate with both standard solutions and samples., (Published by Elsevier Ltd.)

Background: Sulfites are some of the oldest and most widespread preservatives in our food supply. They are food additives that have antioxidant properties, but they are also recorded as allergens by the main international regulatory bodies on food safety because of their adverse health effect. Hence, sulfites maximum concentration in foodstuff is regulated and they must be ensured by the agro-food processing industries. The most widely used technique for the quantification of sulfites is the Modified Monier-Williams (AOAC Official Method 990.28 ). Objective: In this method, SO₂ is released from sulfites and some bound compounds when the sample is mixed with an acid (normally hydrochloric acid, but sometimes phosphoric acid) and heated. The SO₂ is distilled using a stream of nitrogen gas, which carries the gaseous SO₂ into an absorbing solution of hydrogen peroxide (H₂O₂) where it is oxidised to sulphuric acid. The amount of SO₂ distilled into the H₂O₂ is determined by titration with 0.1M sodium hydroxide. Apart from being time consuming (at least 2 h) and the usage of toxic solvents, the method presents some other disadvantages that make it inappropriate as a routine-control technique for the agro-food industry. Hence, the industry demands simple, fast and accurate methods for sulfite level monitoring. Methods: BIOLAN is a SME that develops and commercializes biosensors for quantitative analysis of food quality and safety parameters, based on its proprietary enzyme-based electrochemical biosensor technology platform. This technology enables high accurate and robust analysis with a compact device that help the users to control the quality in an easy and safety manner. Biofish-300 SUL method is a highly specific enzimatic biosensor for the rapid quantification of sulfite, measured as SO₂ content, in crustaceans. It consists on the extraction of sulfite in an aqueous based solution, by the aid of an Ultra-turrax or similar, and its subsequent quantification by the biosensor after previous calibration (3 min). Results: Sulfite in raw shrimp head-on, raw shrimp head-off, and boiled shrimp was analyzed, and performance was examined using naturally contaminated and spiked samples by comparisons with AOAC Official Methods of Analysis SM (OMA) 990.28 . Linearity, selectivity, matrix, consistency, and robustness were evaluated. All results were within acceptable ranges except robustness, which reflected deviation in the sample volume and ultraturrax time compared with the standard assay procedures described in the Biofish 300 SUL Instruction Manual. Accuracy, assessed as a comparison of the Biofish results with the OMA results, ranged from 82 to 115% in all samples except for fortified raw shrimp head-on, in which the low level yielded an accuracy of 138%. The method bias was in general negative in both incurred and fortified high levels, and slightly positive in incurred low levels. Repeatability was very good as shown by the low RSD r values, demonstrating acceptable repeatability precision with results <10% in most of the evaluated values. Regression analyses showed a good correlation between the Biofish and OMA methods with R² = 0.99 in all cases. Conclusions: As a whole, accuracy, recovery and bias within range results indicate that the kit provides accurate and precise sulfite quantification for all the evaluated matrices, confirming that sample preparation and assay procedures produce acceptable results. Biofish 300 SUL has proved to be a suitable tool for monitoring sulfite levels in quality control routines due to its high accuracy, precision, rapid response and ease of use. Highlights: With a simple sample preparation, results are obtained in approximately 3 min, making a big difference with other technologies that require specific skills or tedious sample pretreatments and analysis procedures.

This work reports an in-line electrochemical reagent generation coupled to a flow injection biamperometric procedure for the determination of SO3(2-). The method was based on a redox reaction between the I3(-) and SO3(2-) ions, after the diffusion of SO2 through a gas diffusion chamber. Under optimum experimental conditions, a linear response ranging from 1.0 to 12.0 mg L(-1) (R=0.9999 and n=7), a detection and quantification limit estimated at 0.26 and 0.86 mg L(-1), respectively, a standard deviation relative of 0.4% (n=10) for a reference solution of 4.0 mg L(-1) SO3(2-) and sampling throughput for 40 determinations per hour were achieved. Addition and recovery tests with juice and wine samples were performed resulting in a range between 92% and 110%. There were no significant differences at a 95% confidence level in the analysis of eight samples when comparing the new method with a reference procedure., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A ratiometric fluorescent probe based on a positively charged benzo[e]indolium moiety for bisulfite is reported. The bisulfite underwent a 1,4-addition reaction with the C-4 atom in the ethylene group. This reaction resulted in a large emission wavelength shift (Δλ = 106 nm) and an observable fluorescent color change from orange to cyan. The reaction could be completed in 90 s in a PBS buffer solution and displayed high selectivity and sensitivity for bisulfite. A simple paper test strip system was developed to detect bisulfite rapidly. Probe 1 was used to detect bisulfite in real samples with good recovery.

In shrimps the treatment with sulphiting agents is currently the best option for controlling Melanosis, which is a visual defect of the products that compromises marketability. However, sulphites may cause pseudo-allergic reactions in humans. In this study, 210 samples of shrimps were analysed in order to assess the residual levels of sulphiting agents. A quantifiable sulphites concentration was detected in 76 samples, and these concentrations were higher than the legal limits in eight samples. Considering the important pseudo-allergenic effects caused by these food additives, the non-negligible percentage of 3.8% and the high levels registered in non-compliant samples (up to 1174.1 mg kg(-1)), a strong contrast action based on permanent controls is necessary. Moreover, the levels measured in whole samples were up to four times higher than in the edible parts. These results suggest to consider the introduction of legal limits, related to sulphurous anhydride in the whole product.

Sulphiting agents are commonly used food additives. They are not allowed in fresh meat preparations. In this work, 2250 fresh meat samples were analysed to establish the maximum concentration of sulphites that can be considered as "natural" and therefore be admitted in fresh meat preparations. The analyses were carried out by an optimised Monier-Williams Method and the positive samples confirmed by ion chromatography. Sulphite concentrations higher than the screening method LOQ (10.0 mg · kg(-1)) were found in 100 samples. Concentrations higher than 76.6 mg · kg(-1), attributable to sulphiting agent addition, were registered in 40 samples. Concentrations lower than 41.3 mg · kg(-1) were registered in 60 samples. Taking into account the distribution of sulphite concentrations obtained, it is plausible to estimate a maximum allowable limit of 40.0 mg · kg(-1) (expressed as SO(2)). Below this value the samples can be considered as "compliant"., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The results of the assessment of the dietary exposure to annatto, nitrites, tartaric acid and sulphites within the framework of the second French total diet study (TDS) are reported. These 4 additives were selected from the Bemrah et al. study [Bemrah N, Leblanc JC, Volatier JL. 2008. Assessment of dietary exposure in the French population to 13 selected food colours, preservatives, antioxidants, stabilizers, emulsifiers and sweeteners. Food Addit Contam B. 1(1):2-14] on 13 food additives which identified a possible health risk for annatto, sulphites and nitrites and a lack of data for tartaric acid. Among the composite samples selected for the whole TDS, 524 were analysed for additives (a sample was analysed for a given additive when it was identified as a major contributor for this additive only): 130 for tartaric acid, 135 for nitrites, 59 for annatto and 200 for sulphites. Estimated concentrations (minimum lower bound to maximum upper bound) vary nationally from 0 to 9 mg/kg for annatto, 0 to 420 mg/kg for tartaric acid, 0 to 108 mg/kg for sulphites and 0 to 3.4 mg/kg for nitrites. Based on the analytical results, the dietary exposure was calculated for adults and children, separately, using lower bound and upper bound assumptions. The European ADIs for these 4 additives were not exceeded except for the dietary exposure for sulphites among 2.9% of the adult population, where the major contributors were alcoholic drinks and especially wine under both hypotheses (lower and upper bound).

The acceptable daily intake (ADI) for a considered chemical is by definition the amount of that substance which can be ingested every day during the life time without appreciable health risk. The theoretical risk of exceeding the ADI for benzoates, sulphites, butylhydroxyanisol (BHA) and butylhydroxytoluen (BHT) has often been examined on the basis of worst case scenario. The aim of this paper is to assess the actual intake of the food additives listed above for a group of the Lebanese population (students aged between 9 and 18 years old) likely to be highly exposed to food additives through the consumption of processed foods. Dietary exposure was obtained by combining food consumption data with food additives levels determined by chemical analysis. Food products available in Lebanon and containing added benzoates, sulphites, BHA and BHT were identified. Overall 420 samples of foods and beverages were analysed. The determination of food additives residue levels was carried out according to the official methods adopted in "Lebanese Institute for agronomic research" (IRAL) on food as consumed. The acceptable daily intake (ADI) could be exceeded for sulphites and BHT by a fraction of the population, in particular within children of 9-13 years old. Among all food additive-containing foods, the highest contributors were: soft drinks to benzoates intake, nuts and canned juices to sulphites intake, bread and biscuits to BHA intake and chewing gum to BHT intake.

The modified Rankine colorimetric method for measuring sulfite added to food as a food additive has a low determination limit and is little influenced by interfering substances from foods. However, it can give erroneous results for foods containing Liliaceae Allium. So, four different methods, alkaline titration, a colorimetric method, ion chromatography and qualitative analysis with potassium iodate-starch paper, were examined. It was found that the sodium azide used in the colorimetric method forms sulfur dioxide during bubbling and heating. The proposed colorimetric method can be applied to food containing sulfur compounds, if sodium azide is omitted and 1% triethanolamine solution is used as an absorbent instead of 0.1 mol/L sodium hydroxide solution.

Sulphites are extensively used in the food and drinks industry. Their toxicity has been previously evaluated by addition to the diet or drinking water of laboratory animals. Because interactions between sulphites and food constituents occur, the present work was conducted to determine the subacute and subchronic toxicity of sulphite-bound compounds in a finished product: manufactured biscuits. The studies were performed on Sprague Dawley, rats for 28 and 85 days of dietary exposure. Diets were prepared from sulphited or untreated (controls) biscuits with the addition of sugar, protein, vitamins and minerals according to the nutritional requirements of the animals. Groups of 10 male and 10 female rats were administered diets containing sulphited biscuits at levels of 0, 10, 35 and 75%, corresponding to 10-15, 35-45, 150-170 and 310-340 mg SO2/kg diet. In both studies, no death or clinical abnormalities were reported. Growth rate, food consumption and food conversion efficiency were not affected by treatment. No dose-related changes were observed for haematology, clinical chemistry, ocular examination, renal-function, urinalysis, organ weights or gross and microscopic examinations. The liver concentrations of vitamins A, B1, C and E were not significantly changed except for an increase in vitamin E in high-dose males after 28 days' exposure. Based on these data, the no-observed-adverse-effect level (NOAEL) of sulphites in baked biscuits was judged to be 310 mg SO2/kg diet or 25 mg/kg body weight/day.

The theoretical risk of exceeding the Acceptable Daily Intake (ADI) for sulphites has mostly been examined on the basis of a worst-case scenario. In order to examine the real situation the determination of residue sulphite levels in ready-to-consume foods is required. The aim of this paper is to assess the actual sulphite content of diets obtained from a combination of realistic meals high in sulphite-containing foods. Food products available in Italy containing added sulphites were identified. Overall, 211 samples of foods and beverages (including 85 samples of wine) were collected. The determination of sulphite residues was carried out on the foods which were prepared according to normal domestic practice. It was shown that the diets obtained from these foods would lead to an intake of 23 mg/day in children and 50 mg/day in adults (both slightly above the ADI for respectively a 30 kg child and a 60 kg adult). Among all sulphite-containing foods, the highest contributors to the intake were dried fruit and wine, both ingested without further treatment. The analysis of specific consumption data confirmed the existence of a risk of exceeding the ADI related to sulphite residue levels in wine.

Sulfite is added to foods as an antimicrobial, antibrowning agent, or antioxidant. It also can occur naturally, and is often used in the production of beer and wine. For years the standard methodology for determination of sulfite in foods has been the Monier-Williams method, which is a combination of acid distillation and titration. Recently, AOAC adopted a chromatographic method based on a method developed by Kim and Kim for the determination of sulfite. The method combines ion exclusion chromatography with direct-current (DC) amperometric detection to provide more convenient and accurate quantitation of sulfite. However, fouling of the platinum working electrode results in a rapid decrease in method sensitivity. As a result, standards must be injected before and after every sample, and the electrode must be polished frequently to maintain adequate detection limits. Pulsed amperometric detection overcomes electrode fouling problems by repeatedly and continuously applying cleaning potentials to the working electrode. Using this technique, a reproducible electrode surface can be maintained, and injection-to-injection repeatability is greatly improved. A comparison of method performance for both DC and pulsed amperometric detection is presented. Also investigated was the stability of sulfite samples at varying pH, and in the presence or absence of a preservative.

Background: In view of the development of harmonization provisions for food legislation with regard to additives, the aim of this study is to find out the use of sulfites in minced meats and meat products prepared in establishments located in the Valencia Region., Methods: Following planning of the types of products and number of samples to be researched, the results obtained were evaluated qualitatively and quantitatively for the presence of sulfites, expressed in mg/kg of SO2., Results: The presence of sulfites was found in 65.38% of the samples of beef and pork burgers and in 64.18% of chicken burgers. Minced meat, fresh chorizo (highly-seasoned pork sausage) and raw sausages were more in line with legislation., Conclusions: The extensive use of sulfites in prepared meat products was observed. The imminent application of Community legislation will bring lead to a modification in the practices when preparing these products.

A survey of sulphite levels in a variety of foods including dried fruit, dried mashed potatoes, shrimp, canned mushrooms and fruit juices has been conducted. The levels found ranged from 0 ppm in orange juice to 3722 ppm as sulphur dioxide in dried fruit. The foods were analysed by the optimized Monier-Williams procedure.

A review of the current literature indicates that scientific knowledge of sulfiting agents in food is changing rapidly. Many of the old assumptions about usage of sulfiting agents have been put in doubt by new scientific data. Some basic definitions of sulfiting agents and their chemical behavior in food are presented.

A differential pulse polarographic (DPP) method for the determination of "free" and "total" sulfite in foods was collaboratively studied by 8 laboratories. The collaborators analyzed blind duplicate samples of shrimp, orange juice, peas, dried apricots, and dehydrated potatoes. Collaborators also analyzed the same samples spiked with sulfites at 2 levels, which ranged from 10 to 1100 micrograms added SO2/g. The variability of free SO2 results was excessive for quantitative analysis, but the method can be used for qualitative detection of free SO2. The method for total SO2 determination was suitable for as low as approximately 10 micrograms/g. Recoveries are comparable to those for the official Monier-Williams method at high levels and are superior at low levels. The method has been adopted official first action for determination of total SO2 in the foods studied.

A rapid and accurate analysis for total sulfite as sulfur dioxide has been developed for foods and food products. The method, which combines a selective distillation cleanup procedure with the selective redox titration of sulfite ion by iodine, has been applied to a variety of foods and food products over a period of time with no significant interference encountered in any matrixes other than garlic and leeks. For the foods analyzed, the method typically shows a detection limit of 10 ppm, a relative standard deviation of 7.5% (compared with 10.4% for similar matrixes by the Monier-Williams method), and recoveries of 97.9 +/- 6.4%. Comparison of results for this method with those obtained using the Monier-Williams method showed a mean value for the distillation/titration method of 241 ppm compared with 242 ppm for the Monier-Williams method. A correlation of 0.991 and odds of a difference between methods of 10.7% (Student's paired t-test (1-alpha) X 100) were obtained for those matrixes where no interferences were encountered with either method.

A method is described for the determination of sulfite levels in food products by flow injection analysis (FIA). The method is based on the decolorization of malachite green by SO2, which is isolated from the flowing sample stream by means of a gas diffusion cell. The FIA method has a detection limit in food sample extracts of 0.1 ppm SO2 (3 times peak height of blank), which corresponds to 1-10 ppm SO2 in a food product, depending on the extraction procedure used. At the 5 ppm SO2 level in a food extract, the precision of replicate injections is +/- 1-2%. The method was tested on a variety of both sulfite-treated and untreated food products and the results compared favorably with those obtained by the Monier-Williams, colorimetric (pararosaniline), and enzymatic (sulfite oxidase) methods. The average differences from the FIA results were 19, 11, and 12%, respectively, for those samples (n = 12) above 50 ppm SO2. At lower levels the results were somewhat more erratic due to inaccuracies of the various methods at low concentrations.

Recently, a product (SULFITEST; Center Laboratories) has become available for detecting the presence of sulfiting agents in foods. Testing with SULFITEST by the indirect method (ie, holding the test strip above the food product) or the direct method (ie, touching the test strip directly on the food) was associated with false negative results in five out of nine acidic sulfite-containing foods. Quantitative studies also confirmed that low pH conditions and/or the presence of ascorbic acid caused SULFITEST results by the direct method to significantly underestimate known concentrations of sulfites. Dependence on this sulfite detection strip may lead to unrecognized ingestion of sulfiting agents, especially in acidic and/or ascorbic acid-containing foods.